The invention relates to a tool for removing a core of bone and more particularly for enabling a surgeon to remove a cylindrical core of bone in vivo from a patient.
One relatively common surgical procedure calls for removal of a cylindrical core of medulla bone from a living patient and grafting elsewhere in the patient's or someone else's body. This is accomplished by making a minimal incision over the illiac crest and then driving a cutting tool into the bone to remove a core.
A variety of such instruments have been proposed in the past for removing bone segments and cores. For example, the patent to Velasco 847,133 describes an arrangement with a springloaded extractor for withdrawing a disc-shaped fragment of bone. The patents to Ackermann 2,919,692 and Elias et al 3,850,158 show other medical tools for extracting fragments of bone.
The present invention relates to a unique tool which has a number of substantial advantages in comparison with tools utilized in the past. According to the present invention, the tool is formed as a metal cylinder, preferably of stainless steel, having an internal bore extending along the cylindrical axis from an externally honed cutting edge. After insertion through a minimal incision, the tool is driven into the bone by the surgeon so that a core of bone is pushed into the bore. Utilizing an externally honed cutting edge insures that the bone is not compressed within the bore and may freely enter the same. A plurality of radially extending teeth, for example, three teeth separated by 120.degree. are provided within the bore adjacent the edge for preventing rotation of the core.
A second bore extends laterally through the instrument for receiving an extraction handle. When the tool has been driven to the desired depth, the insertion handle is placed through this laterally extending bore and the tool rotated. The radially extending teeth prevent rotation of the core which, accordingly, breaks at the cutting edge. The teeth further engage the core as it attempts to rotate so that the core can now be easily removed intact with the tool. The teeth also form grooves along the length of the core bone which, after grafting is complete, provide additional bone strength as the three grooves are filled with corticle bone. In addition, these channels provide a means of equalizing the pressure within the bone so that the core can be more easily removed.